Classification Of Metamorphic Rocks

Classification Of Metamorphic Rocks

Ø     Metamorphic rocks have been variously classified on the basis of texture and structure, degree of metamorphism, mineralogical composition and mode of origin etc.

Ø      A very general two-fold classification based on the presence or absence of layered structure or

FOLIATION as defined above is as follows:

(a) Foliated Rocks

Ø     All metamorphic rocks showing development of conspicuous parallelism in their mineralogical and structural constitution falling under the general term foliation are grouped together as foliated rocks.

Ø      The parallelism indicating features include slaty cleavage, schistosity and gneissose structures

Ø         Typical rocks included in this group are slates, phyllites, schists and gneisses of great variety.

(b)Non-Foliated Rocks

Ø Included in this group are all those metamorphic rocks characterised with total or nearly total absence of foliation or parallelism of mineralogicaJ constituents.

Ø Typical examples of non-foliated rocks are quartzites, hornfels, marbles, amphibolites and soapstone etc.